Hydroxy-functionalized liquid-crystalline polyazomethines I. Synthesis, characterization and structure-mesogenic behaviour relationship

Abstract

A new series of polyazomethines based on hydroxy-functionalized mesogenic units has been synthesized and characterized. Different structural variations have been checked in order to obtain mesogenic polyazomethines with low melting temperatures and a broad nematic range. Completely conjugated mesogenic units with a lateral substituent or alteration of coaxiality are shown to be the most suitable structural variations. No mesogenic behaviour was observed for polyazomethines with a flexible mesogenic core due to unfavourable conformational equilibrium. Polyazomethines have complex thermal behaviour and show an increase in the degree of polymerization on annealing.